Early detection of lung disease in preschool children with cystic fibrosis

A multimodal approach to detect and monitor early lung disease in cystic fibrosis

Introduction: In the early stages, lung involvement in cystic fibrosis (CF) can be silent, with disease progression occurring in the absence of clinical symptoms. Irreversible airway damage is present in the early stages of disease; however, reliable biomarkers of early damage due to inflammation and infection that are universally applicable in day-to-day patient management have yet to be identified.Areas covered: At present, the main methods of detecting and monitoring early lung disease in CF are the lung clearance index (LCI), computed tomography (CT), and magnetic resonance imaging (MRI). LCI can be used to detect patients who may require more intense monitoring, identify exacerbations, and monitor responses to new interventions. High-resolution CT detects structural alterations in the lungs of CF patients with the best resolution of current imaging techniques. MRI is a radiation-free imaging alternative that provides both morphological and functional information. The role of MRI for short-term follow-up and pulmonary exacerbations is currently being investigated.Expert opinion: The roles of LCI and MRI are expected to expand considerably over the next few years. Meanwhile, closer collaboration between pulmonology and radiology specialties is an important goal toward improving care and optimizing outcomes in young patients with CF.

Microbiological yield from induced sputum compared to oropharyngeal swab in young children with cystic fibrosis

BACKGROUND

Standard respiratory sampling in young children with cystic fibrosis (CF) is by oropharyngeal swab (OPS) as they cannot spontaneously expectorate. Sputum induction (IS) has been poorly investigated in this population. We aimed to compare the bacteriological yield of OPS vs. IS in young children with CF.

METHODS

Sequentially paired OPS followed by IS samples was collected in children <5years of age attending a CF clinic in Cape Town, South Africa.

RESULTS

IS was successfully paired with OPS in 98/113 (85%) attempts in 32 children (mean±SD 19±16months), with no serious adverse events. IS culture yield for any CF-associated bacteria from IS was 46% vs. 28% from OPS (p=0.01). The sensitivity, specificity, PPV and NPV of OPS compared to IS in isolating CF-associated bacteria were 56%, 96%, 93%, and 72% respectively.

CONCLUSION

Sputum induction is feasible, safe and superior to OPS for detecting CF-associated bacteria in young children with CF.

Multiple breath nitrogen washout: a feasible alternative to mass spectrometry

BACKGROUND

The lung clearance index (LCI), measured by multiple breath washout (MBW), reflects global ventilation inhomogeneity and is a sensitive marker of early cystic fibrosis (CF) lung disease. Current evidence is based on a customized mass spectrometry system that uses sulfur hexafluoride (SF6) as a tracer gas, which is not widely available. Nitrogen (N2) washout may be better suited for clinical use and multi-center trials.

OBJECTIVE

To compare the results obtained from a N2 washout system to those generated by the SF6 based system in healthy children and children with CF.

METHODS

Children with CF were recruited from outpatient clinics; healthy children were recruited from the Research4Kids online portal. Participants performed MBWSF6 (Amis 2000, Innovision, Denmark) and MBWN2 (ExhalyzerD, EcoMedics, Switzerland) in triplicate, in random order on the same day. Agreement between systems was assessed by Bland-Altman plot.

RESULTS

Sixty-two healthy and 61 children with CF completed measurements on both systems. In health there was good agreement between systems (limits of agreement -0.7 to 1.9); on average N2 produced higher values of LCI (mean difference 0.58 (95% CI 0.42 to 0.74)). In CF the difference between systems was double that in health with a clear bias towards disproportionately higher LCIN2 compared to LCISF6 at higher mean values of LCI.

CONCLUSION

LCIN2 and LCISF6 have similar discriminative power and intra-session repeatability but are not interchangeable. MBWN2 offers a valid new tool to investigate early obstructive lung disease in CF, but requires independent normative values.

Cystic fibrosis in neonates and infants

Cystic fibrosis (CF) is a common autosomal recessive disorder, characterized by chronic bronchopulmonary infection, pancreatic insufficiency, and subsequently, other multisystem complications. Most children are diagnosed before school age. Here we review the pathophysiology of the condition, the age-related presentations of CF up until school age, and the appropriate use of diagnostic tests. A specialist centre should supervise treatment. There are exciting new advances in monitoring techniques in the preschool years, including CT scanning, bronchoscopy and gas mixing indices. Recent advances in the knowledge of the molecular biology of CF hold out the hope of specific therapies which can reverse the underlying defect causing death from CF lung disease.